The present invention relates to electric motors; and more particularly, to the field case housing and/or fan baffle of electric motors.
Electric motors are used in a variety of applications, including power tools. Such electric motors typically include a motor shaft, a motor armature, magnets, a fan baffle, a commutator assembly, brush holders and electrical leads. The electrical leads selectively link brushes to a power source. The motor armature is fixed for rotation with the motor shaft and a series of copper conducting wires are wound in various patterns about peripheral slots. Ends of the wires are fused to the commutator. The commutator is fixed for rotation with the motor shaft and provides an electrical connection between the rotating armature and the stationary brushes.
These components are generally housed within a field case housing. Performance is improved by accurately locating the armature and magnets with respect to each other within the field case housing. Consequently, it is desirable to form the housing so that warping during the injection molding process of the housing is reduced. It is also desirable to locate the armature and magnet into their close proximity without the armature impacting upon and damaging the magnets during assembly. Additionally, it is desirable that the assembly process be facilitated by guiding screws from insertion apertures to receiving apertures without being drawn off course by the effects of the magnets. One or more of these, as well as other desirable features, may be selectively accomplished by using various aspects of the present invention.
In accordance with one aspect of the present invention an electric motor assembly including a field case housing and an end plate is provided. The field case housing has a substantially cylindrical wall segment, an end segment and a flange all having a substantially constant wall thickness. The flange having a plurality of flange reinforcing ribs connected to the wall segment and having a plurality of apertures through which attachment members connect the housing to the end plate and having reinforcing bosses around the plurality of apertures. The end plate is adapted to cover the open end of the housing attached to the flange. The end segment, the wall segment and the flange are molded as a single, integral part and the plurality of flange stabilizing ribs, the plurality of end segment stabilizing ribs and the substantially constant thickness is adapted to reduce warping of the housing during a molding process.
In accordance with another aspect of the present invention an electric motor assembly is provided. The assembly has a cylindrical guide member associated with a screw insertion aperture having a diameter and located in a field case housing or a fan baffle. A conical guide member is associated with a screw receiving aperture in the other of the field case housing and the fan baffle. The conical guide member has a distal end which is larger than a diameter of the screw insertion aperture. At least one magnet is located between the cylindrical guide member and the conical guide member which exerts a magnetic force on a screw passing from the cylindrical guide member to the conical guide member. The cylindrical guide member is adapted to insure a tip of a screw passing through the cylindrical guide member is guided to a point within the diameter of the conical guide member.
In accordance with yet another aspect of the present invention, an electric motor assembly,with field case housing and oppositely disposed motor magnets associated with the housing is provided. A fan baffle is associated with the housing adjacent the oppositely disposed magnets. The fan baffle has a transverse wall with an aperture therethrough and at least one guide wall extending from the transverse wall adjacent the aperture. The at least one guide wall is adapted to guide an armature past the oppositely disposed magnets without contacting and damaging one of the oppositely disposed motor magnets.
In accordance with another aspect of the present invention, an electric motor assembly having a motor magnet assembly and a fan baffle adjacent thereto is provided. The fan baffle has a transverse wall with an aperture therethrough and at least one guide wall extending from the transverse wall adjacent the aperture. The at least one guide wall is adapted to guide the armature past the motor magnet assembly. The fan baffle also has a cylindrical guide member associated with a screw insertion aperture or a conical guide member associated with a screw receiving aperture, where the conical guide member has a diameter at its distal end which is larger than a diameter of the screw insertion aperture. A field case housing is associated with the motor magnet assembly and the fan baffle. The field case housing has the other of the cylindrical guide member or the conical guide member. The cylindrical guide member is adapted to cause a tip of a screw passing through the cylindrical guide member to be guided to a point within the diameter of the conical guide member.
Further areas of applicability of various aspects of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention.